This is an interesting discussion of a source I’ve read in the past. I was aware of the problems with Tacitus’s use of the Germanic tribes as a ‘comparison’ with Roman society. It’s fairly clear that Tacitus cannot be considered a primary source, since he never witnessed any of the things he recounted himself. Archaeology and other sources need to be read in conjunction with Classical sources.

Source: A Heathen’s Concern for Germania: Understanding Tacitean Historiographical Problems